I'd like to make a mason bee house

Asked July 17, 2017, 9:25 PM EDT

hi, what is the best time of year to put the mason bee house outside? Is it too late to put them out now (it's mid July now)? Do you have any recommended information about how to build a mason bee house? do you recommend using the (baking) paper inserts? I have several untreated 2x4s, can I screw them together to make it thicker and drill holes for a bee house or should I use a solid 4" thick untreated wood?

Larimer County Colorado

1 Response

Thank you for wanting to make a home for Mason bees. It is too late to put out a house for them this year. but it is a good time to get things ready for next year. The bees are active from March to June. The bees that have overwintered in their house, emerge from their cocoons and engage in life activities. The males have a short life. They emerge first, feed and wait for the females. After they mate, the males die and the females are active with building a cell, with food, for each egg. They lay an egg each day for the next 25-30 days. This is when we see them at work pollinating. At the end of June, the females tasks are done, and they die.

The eggs hatch about a week after being laid, and spend the next four weeks eating the food provided by their mothers. Without leaving the cell, they spin a cocoon and from June to September they transform from larvae, to pupae to adult. They remain, dormant and continue to mature until late winter /early spring, when they emerge and the life cycle begins again.

At the end of this note I have placed links that include building houses, and other information. Strips of wood that can be taken apart and cleaned and sterilized with a mild bleach solution are better than a solid block of wood. Mold is deadly for them and it cannot be thoroughly removed from a wood block.

Choosing nesting materials. Pull-apart wooden blocks, cardboard with paper lining, drilled blocks and homemade paper tubes can all work well for nesting. Pull-apart wooden blocks can be a great material since they’re porous (allowing moisture to escape), and they’re easy to clean, sanitize, and reuse.

While I don't recommend paper because of threat of mold, they make a great project for kids to make on their own. Drilled blocks must be made new each year — they can get infected with microscopic pests and cannot be cleaned.

In February, before the adults emerge is the best time to put up a house. August is a good time to take down the used houses, that the adults hatched out of, clean and refurbish, to get them ready for next year. The bees are healthier, with fresh houses each year, and will seek them, if you don't provide them.

As I said before, paper, wax paper or recycled cardboard for DIY tubes are not good choices. Mold can grow on these and can destroy the hibernating bees.

I think baking paper inserts may not be a good idea, because the dyes that give color might affect the pupa. I have read that newspaper print, because of the dyes, is not good for them.

The best material I have found is parchment paper, which is made from animal skin. I don't know if you can clean it, or would want to.

It is recommended that you keep a small area of mud near, but not under your Mason bee house. The female needs mud to encase each egg. If she does not have to look for mud, and there is plenty of food, she will not stray. Unlike other bees, each female lays eggs; and Mason bees are individuals, not part of a hive. The female can control the placement of the babies in the tubes. She puts the female eggs in first. The male eggs are not fertilized and they are laid last, closest to the (sealed) opening of the tubes.

A good Mason bee house has to have tubes that are at least 6" long, because the female lays 5-6 eggs /tube, each chamber is about an inch long. The chamber should be nest tunnels that measure between 5/16” and 3/8” in diameter.

Place your house in a place that is protected and hard for birds to find. Many think a Mason bee nest is very tasty.

Good locations: South or southeast facing wall or the wall of a garage, garden shed or house. Somewhere that gets morning sun and as much sun throughout the day.
Bad locations: On a tree as they may shade the box, allow squirrels to disrupt the bees, and have movement on windy days or in total/partial shade.

Mason bees favorite food is the pollen from fruit trees and berries, and the active portion of their lives corresponds with the flowering season of these plants.

You can even rent the bees and their houses. At the end of the year, send the bees and their house back. The next year you can rent more bees and get a clean house for them too.


I like the instruction on building a Mason bee house at this side.


Here is another construction guide. http://boingboing.net/2014/05/16/build-your-own-mason-bee-house.html

This website has lots of information on several pages about Mason bees. http://olypollinators.blogspot.com/p/mason-bee-life-cycle_04.html

This site sells reusable and cleanable blocks for the bees to nest in. http://www.masonbeehomes.com/bee-houses-mason-bee-pro-bee-block

Great, no nonsense information may be found here. https://www.parentmap.com/article/keeping-mason-bees-10-expert-tips-for-families

Thank you for your great questions, I enjoyed researching and learning more about Mason bees.